6.S078 - Computer Architecture: A Constructive Approach

AWB - Architect’s Workbench

Joel EmerComputer Science & Artificial Intelligence Lab.Massachusetts Institute of Technology

February 10, 2012 L2-1http://csg.csail.mit.edu/

6.S078

What is AWB?• An set of abstractions that enables the

plug and play of modules to facilitate design

• A suite of tools to support rapid modular construction and analysis of designs• GUI and command line interfaces• Released under GPL (specific

projects/models may not be)

Why Modularity?• Speed of development• Well thought out interfaces => better design• Cooperative development• Sharing components between projects• Improved robustness through reuse • Facilitates design trade-offs,

e.g., speed/complexity• Design space experimentation w/o code bloat• Factorial development and evaluation

AWB ProjectsAWB

Asim

Alpha

EV8 EV9

X86

Secret

…

LEAP

HASIM

Alpha

Secret

…

Airblue

802.11

Softrate

…

H.264

…

AWB Glossary• Packages (codebases) - .pack files:

• are stored in repositories and checked out, or• are referenced locally on a system• become part of a users local workspaces• are versioned• can be grouped into sets called bundles

• which can be checked out together• contain modules, models (projects) and

benchmarks

AWB Glossary• Models (projects) - .apm files:

• are a description of a hierarchy of modules• are turned into a build directory tree via a

configuration step

• Benchmarks - .cfg files:• are a description of a run of a design• are turned into a run directory tree via a

setup step

AWB Glossary• Workspaces

• are a place to work on awb-based projects• can contain multiple packages• can contain multiple build directories,

• which can contain multiple benchmark runs

http://asim.csail.mit.edu/redmine/projects/awb/wiki/Glossary

AWB Operation Example

Repositories Workspace

AWB module details Modules represent the unit of “swapability” in source code

• Each module is defined in an .awb file• Textual %name and %description of the module

• List of the %source files that comprise the module’s code• E.g., C, C++, BSV, Makefiles or Scons files.

• Modules also %provide an AWB type (different from C++ type)

• E.g., branch_predictor, fetch, decode, execute, cache

• Modules can %require modules of specific AWB types• E.g., cache may require a pre_fetcher and different prefetch

schemes would provide the same AWB type “pre_fetcher”

• Modules can describe %parameters the user can vary• Parameters can be static (compile time) or dynamic (run time)

Module Configuration – Example .awb File %name APE Unit Tester %desc APE – The AWB Plugin Exerciser %attributes ape test

%provides system %requires feeder ape_driver isa

%source –-public ape.h %source –-private ape.cpp ape-util.cpp

%param MAX_INST_BUF_SZ 1024 “Number of instr buffer entries” %param --global MAX_IDLE_CYCLES 256 “Maximum number of idle

cycles”

http://asim.csail.mit.edu/redmine/projects/awb/wiki/Awb_file

Modules

Multiple modules may have the same awb type, but must have unique %names.

If two modules provide the same awb type then this is an assertion that they can be swapped for one another and that the result will be a coherent set of code that will successfully build.

From Modules to Models

• A model (project) is an interesting configuration selected by the user:

• All parameter values are set (unset ones use their default)

• All “requires” choices are made between alternative modules

• Stored in a .apm file

• Created using apm-edit GUI

Example Module Hierarchy

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MC N

D R X C WF

B

Simple Example: Module Selection

B

B

B

B

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D R X C WF

BB

D R X C WF D R X C WF

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MC NC M N

Complete Example: Module Selection

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BB

B

B

B

B

Default Choices via Attributes

B

B

B

B

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MC N

D R X C WF

B

X

Modularity & Factorial Coding/Experiments

SC

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MC N

SM

RC

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RM

RC

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RM

AWB Tools• Awb-shell

Scriptable command line tool for creating/manipulating a workspace, creating/obtaining packages and configuration, building and running models

• AwbGUI for accessing most of the functionality of awb-shell

• Apm-editGUI for creating/editing models

• More toolsApm-find-replace, plotshell, regression.launcher, awb-run …

Workspace• A personal directory tree to work on

models and experiments

• Created with awb-shell command: % awb-shell new workspace <directory> % cd <directory>then: % awb-shellor: % awb &

http://asim.csail.mit.edu/redmine/projects/awb/wiki/AWB_example_setup_command_line

Determination of Current Workspace

Most tools operate in the context of a workspace. The current workspace is determined by a trampoline script (asimstarter) that runs as a prelude to the tools themselves. That script determines the current workspace by:

• Looking for environment variable $AWBLOCAL• internal mechanism – should not be used by users

• Checking if current working directory is in a workspace• this is the preferred technique

• Looking for a default workspace directory• as specified in ~/.asim/asimrc

• Using <prefix>/share/asim/ws• used to bootstrap a user on first use of an awb-based tool

Workspace Structure<workspace-name>/ awb.config - configuration file for this workspace src/ - area for checked out packages

<package-A>/<package-B>/...

build/ - area where models are built and run <project-A>/...

pm/ - source build tree obj/ - object tree of built objects

src/ - source tree (links to module sources)<model> - built executable of model Makefile - synthesized Makefile

bm/ - area where benchmarks are run<benchmark-A>/...

run/ - area where experiments/regressions run

http://asim.csail.mit.edu/redmine/projects/awb/wiki/Glossary#Workspace

Awb.config file format[Global]VERSION=1.4Class=Asim::Workspace[Vars]shared=/usr/share/asim/packages

[Paths]# Directory containing actual benchmarksBENCHMARKDIR=/usr/share/asim/benchmarks# Path where we search for ASIM filesSEARCHPATH=src/leap:…:${shared}/awb/HEAD

[Build]# Make flags for all model buildsMAKEFLAGS=

Options for many tools that can be inserted in awb.config can be obtained via –options switch, e.g.,

% awb-run –options [awb-run] BUILD=1 BUILD_ALL=0 BUILD_DISTCC=0 …

Search for options proceeds from:

1. <workspace>/awb.config2. ~/.asim/asimrc3. <prefix>/etc/asim/asimrc

http://asim.csail.mit.edu/redmine/projects/awb/wiki/Awbconfig

Shared / Private Packages

Packages shared by all users on a machine:

<prefix>/share/asim/<pkg-name>/<release> Obtained via:

% awb-shell use package <pkg-name>[/<version>]

Private packages:<workspace>/src/<packages>

Obtained via checkout…

RepositoriesThe CVS, SVN, or GIT repositories described in:

1) ~/.asim/repositories.d/<package-name>.pack2) <prefix>/etc/asim/repositories.d/<package-name>.pack3) <prefix>/etc/asim/asim.pack

Check out with command: % awb-shell checkout package <pkg-name>[/<version>]

Get updates with command: % awb-shell update package <pkg-name>|all

Commit changes with command: % awb-shell commit package <pkg-name>|all

http://asim.csail.mit.edu/redmine/projects/awb/wiki/AWB_example_setup_command_line

Package Structure Details<package-name>/

admin/ - awb-managed administrative files config/ pm/ - model configurations …/…/<model-A>.apm …/…/<model-B>.apm bm/ - benchmark configurations …/…/<benchmark-A>.cfg …/…/<benchmark-B>.cfg

modules/ - modules …/…/<module-A>/ <module-A>.awb - module description <module-A>.h - module source <module-A>.cpp <module-A>.bsv

<miscelaneous>/ - package specific directories

http://asim.csail.mit.edu/redmine/projects/awb/wiki/Glossary#Package

Package Search Path• To unify the view of all the files in all the

packages coming from different repositories the directories of all the packages are treated by most awb-related tools as if they were overlaid in a single view, like a ‘uniondir’ file system.

• File references resolved through search of all package directories in the search path

• Specified in SEARCHPATH= line in <workspace>/awb.config

http://asim.csail.mit.edu/redmine/projects/awb/wiki/Glossary#Uniondir

Manipulating the Search Path

• Automatic: Checking out/using a package adds it to the

path by default

• Semi-automatic Run command:

% awb-shell add package <directory>

• Manual Edit awb.config

Model BuildSince a model is created from a pool of modules, the build paradigm adds a new step to “configure” a model source tree from that pool of modules.Therefore a workspace has:

A “source” area with a pool of module sources where users add modules and make changes to existing modules…

A “build” area for “configured” models that is managed almost entirely by the awb infrastructure…filled with build trees populated with links to the actual source files and synthesized source files.

Note: the actual tool used to do the configure is determined by the ‘type’ of the model.

Model Configurations• Found in:

config/pm/.../<model>.apm

• Contains: module hierarchy module parameters

• To perform the configure a project, cd into your workspace and type:

• % awb

AWB- GUI

The ‘configure’ button invokes the proper configure tool as determined by the model type. (See apm-edit for details)

AWB- GUI

Runlog shows the command line tool invoked. Should have been leap-configure, which creates a build directory.

AWB- GUI

The ‘build’ button invokes ‘make’ (or ‘scons’) in the build tree created by the configure script.

AWB- GUI

The ‘setup’ button invokes the proper benchmark setup tool as determined by the model type. (See apm-edit for details)

AWB- GUI

The ‘run’ button invokes the ./run script in the benchmark directory created by the benchmark setup script.

AWB- GUI

http://asim.csail.mit.edu/redmine/projects/awb/wiki/AWB_example_build_GUI

Awb-shell% awb-shell awb> configure model <model>awb> build modelawb> setup benchmark <benchmark> awb> run benchmarkawb> quit

Example:

<model> = config/pm/leap/demos/hello/hello_hybrid_exe.apm

<benchmark> = config/bm/leap/demos.cfx/benchmarks/null.cfg

http://asim.csail.mit.edu/redmine/projects/awb/wiki/AWB_example_build_command_line

Apm-edit - GUI

Apm-edit - GUI

Alternative module operation – replace module in tree with module or submodelModule properties operations - edit module, open shell in module’s source directory.

Model Configuration – Example .apm File

[APE]File=pm/system/ape.awb[APE/Requires]

feeder=TraceFeederape_driver=APE Null Driverisa=IPF ISA[TraceFeeder]

File=feeders/inst/trace/tracefeeder.awb[TraceFeeder/Requires]

traceinstruction=IA64TraceInst

http://asim.csail.mit.edu/redmine/projects/awb/wiki/Apm_file

SubmodelsA predefined hierarchy of modules specified in an .apm file (called a submodel) can be used to fill in for a module if the root of the submodel matches the requires for that point in the tree.

Creating a submodel from a module in the middle of an existing tree. Right click and select ‘insert->as root’. Then click the menu ‘file->saveas’ to create a new .apm file.

Discuss other properties that can be set…

Acknowledgements

IntelMohit GambhirMichael PellauerMichael AdlerCarl Beckmann

MITElliott Fleming

DECDavid Goodwin

Resources

http://asim.csail.mit.edu/